When the tide goes out

Warren Buffett's classic quote : "It's only when the tide goes out that you learn who's been swimming naked" may have been about the financial markets, but it's just as applicable to evidence-based care.
One of my current projects is researching the assurance processes used within health and care, to recommend a model for assuring clinical content applicable nationally.
It should come as no surprise, but most of the 'evidence based care' pathways we use may be more 'I'm the expert and this is what I think'. Developing pathways in the past has been down to a medical consultant doing it her/his way, then writing it down and publishing.
In Lean service improvement methodology, one of the first steps is to define the pathway, so there's certainly merit in this. But once it's published, who questions it? Who even measures (accurately) whether it's better or worse than any other pathway, and with what scope of measurement (eg cost for this pathway, vs cost for caring for this group of patients)?
Now I'm certainly not suggesting that you question every pathway. I am suggesting you put appropriate measurement regime in place. And I'm certainly suggesting that you question the assurance process which led to the pathways you use, whether it is robust!
For the record, there are some outstanding assurance processes, including NICE (National Institute for Health and Care Excellence) and NHS QIS (National Health Service Quality Improvement Scotland) which have very robust processes for their legally binding guidelines - but most assurance processes consist of a self-selecting panel (and often on the basis of who's prepared to put the effort in) reviewing to a greater or lesser extent and comparing the results with no others or few other pathways.